Halo JC 3+
Phono Preamplifier
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
A new improved version of our award-winning JC 3
Six years ago we asked legendary audio designer John Curl if he would create a reasonably priced Parasound
Halo phono preamplifier in the spirit of his masterpiece, the Vendetta. Three years later we introduced the
remarkable Parasound Halo JC 3 which has earned rave reviews from the audiophile press and a legion of
vinyl enthusiasts. During the design phase of the original JC 3, Curl had rejected variable load adjustment
because potentiometers generally have higher thermal self-noise, which is an anathema to the creation of
an ultra low noise phono stage. Our decision to bring the JC 3 to market with limited switched input load
impedance choices disappointed some vinyl enthusiasts who consider input load fine-tuning to be essential
for certain cartridges.
Curl and circuit board designer Carl Thompson eventually consented to a redesign with variable load
impedance adjustments, but with these caveats for the potentiometers: 1) They must comply with stringent
performance requirements. 2) They must be manufactured by Vishay, a highly-regarded manufacturer of
low-noise component parts.
We took this opportunity to make additional performance improvements. Curl has narrowed the spectrum
of Johnson/Nyquist noise in the resistor that loads the input stage. Circuit-board designer Carl Thompson
tweaked the phono module board layouts to further optimize every performance parameter. The phono
modules copper circuit board traces now have 24 karat gold-plating where each part is soldered to provide
exceptional transparency and musical detail.
As a result of these changes, the MC signal to noise ratio is improved to 87dB, A-weighted. MM gain has
been increased slightly to 48dB, while MC gain has been lowered from 68dB to 64dB so that extra-high
output MC cartridges won’t cause the JC 3+ to overload the inputs of some line stage preamps or integrated
amps.
The JC 3+ power supply has also been significantly upgraded with 47 percent larger low-ESD power supply
filter capacitors and an 82 percent larger R-core power transformer. This provides much greater current
reserves for head-snapping dynamics. Finally, we added an on/off switch for the front P logo illumination.
